This invention relates to the blocking of motor stator windings, and, in particular, to the blocking of the inner diameter of the windings.
When windings are inserted into the winding receiving slots of a stator assembly for a motor, for example, the end turn portions of the windings are not in proper or acceptable form. Commonly, the end turns must be blocked to have an inner diameter, an outer diameter, and a height which meets with certain industrial standards and specifications. The windings are typically blocked by a mechanism having tooling which sequentially blocks the outer diameter, the inner diameter and the height of the winding end turns.
The stator winding blocking devices conventionally include three tooling parts, an outer diameter block, an inner diameter block, and a compression ring which blocks the height of the windings. The outer diameter block is made of discrete segments which form a continuous ring in the block condition. The inner diameter block is made of discrete segments and forms a contiguous circle prior to blocking, as is shown in FIG. 1A of the drawings, labeled prior art. To block the windings, the outer diameter is initially blocked by compressing the outer diameter block. The outer diameter block segments are arranged around the windings and moved radially inwardly to bring all stray winding coils inside the predetermined radius. When the outer diameter block is in its block position, the coils are presented with a contiguous circular surface.
The inner diameter is blocked next. The inner diameter block segments are arranged inside of the coils and moved radially outwardly until a predetermined inner diameter of the windings is reached. Because the inner diameter block segments are separated, the windings are presented with a discontinuous circular surface which define gaps G, shown in FIG. 1B of the drawings.
Lastly, the windings are blocked for height using the compression ring. When the windings are compressed, the coils or winding end turn portions "squirt" or move into the gaps G of the inner diameter block. Therefore, to insure that these "squirted" windings are within the proper inner diameter tolerances, the inner diameter block has to block the windings more severly than would be necessary if this "squirting" had not occurred. The extra blocking, which is made necessary because of the required blocking dimension imposed on the motor and the likelihood of wire "squirts", can damage the windings. The winding damage, in turn, eventually results in motor failure.
Applicants are unaware of any commercially available inner diameter blocking tooling which presents the windings with a substantially continuous gap-free surface when blocked.